Inhibited detergent composition



Patented Apr. 18, 1939 UNlTED STATES PATENT OFFICE w v 2,155,046 mnmrrnn DETERGENT COMPOSITION No Drawing. Application February 29, 1936', Serial No. 66,436. Renewed March 8, 1939 10 Claims.

The present invention relates to alkaline detergent materials for metal pieces, especially those .having surfaces of tin, zinc, iron or aluminum,

which is eflective to clean the same without deleterious action such as corrosion, dissolution, spangling or checking.

The use of alkaline agents is well known for cleaning metal were of zinc, aluminum-or tin plate, such as'milk cans, baking pans, etc., which have oil,.grease or fat, burned-on flour, milk curds, etc.

concentrations and. at the elevated temperatures and the time of action ordinarily employed.- It is also known that. inhibiting agents are added to minimize or prevent. such deleterious action. Some of these inhibited detergent compounds are efi'ective when the metal pieces are washed in wooden, glass. or enamel tanks or under other conditions which 'do not produce additional deleterious influences. For example, there may be found baths which: are efiective in. a glass tank, but which are not .efiective in a galvanized iron tank, or in aniron tank, when the metal being cleanedis in contact with the metal of the tank. The tank metaland the. metal piece. to be cleaned establishelectrical contact and are in a common bath; thus 1 establishing. galvanic action. By this condition different electrical potentials between the two metals and the solution cause a. galvanic flow-of electricity, or alteration .of 'the single potential-which exists between each metal alone and the cleaning bath. The same conditions may occur in a non-conductive tank where difierent kinds of metal pieces are being cleaned in contact with each' other. The alteration of conditions as a result of these galvanic couples can be suflicient to produce corrosion or injury with cleaning baths which are otherwise satis-' factory.

The present invention aims to produce a detergent compound whichis more universally effective for various metals to be cleaned, and'for use in glass,.zinc, galvanized iron, or iron tanks, and

' 5" for usesimultaneously with difierent metals to.

be-cleaned. It is an object to provide a compound in solid form to be added to water to form a bath, or else to provide the bath itself. Al-

though the invention provides a bath which is efiective 'where galvanic force exists, it' should be understood that the conditions which are encountered in the galvanic action are the result: of-

forces which exist in the absenceoi agalvanic couple, namely the electrical potential existing between the bath and themetal to be cleaned. This potential is involved in the deleterious action to be avoided. The. bath, therefore, as a It is realized that baths oi. these agents are usually injurious tothe metal in the.

above and below this range.

merits herein made are withreference to such a 10 range of concentrationgbut it is not to be assumed that the general statements are not-applicable The temperature and time of exposure to the cleaning agent also havea bearing on the action, and unless other- 15.

wise specified generalstatements are to .be considered with reference to conditions commonly encountered in commercial practice.

Common alkaline reacting detergents are soda ash, caustic soda, trisodiumphosphate, sodium 20 silicate, borax, etc. Several of these'may be used in weak solutions, such as 0.15% to .3% concentration when cold without giving corrosion, or

other deleterious action, but the cleaning action is not effective. When heated to secure effective cleaning, there is also-corrosion or other adverse 2'6 action. Addition agents forinhibiting corrosion are recognized but they have limited or specific action depending upon concentration and kind of alkali, concentration of inhibiting agent,.'tem- 80 perature, and time- Sodium hypochlorite is one such agent. Chromates are recognized inhibitors for mild alkaline detergents.

Calcium .hypochlorite is not a successful inhibitor for use with the general run" of alkaline detergent when used for tin or aluminum-surfaces, and for use in glass, i'ron,.zin'c or galvanized tanks.- Neither are zinc salts, such'as 'zinc sulphate, suitable inhibitors under these conditions. The present invention is based 1 upon the discovery that calcium hypochlorite' anda zinc salt such as zinc sulphate,-may beused' in combia nationas a corrosion inhibiting mixture for alka line detergents under the described conditions. In order best to explain the invention, typicalexamples of the invention are here given, andlater discussed.

j l lzample No. 1

Per cent. Trisodium phosphate monohydrate 32. Anhydrous sodium carbonate 32. 25 1 Sodium metasilicate 20,00 -Calcium= 'hypochlorite- (IO- 72% available chlorine) 5,00 Anhydrous zinc sulfate n10.00- Wool Orange 2---C'v .25-

Y ,-Anhydrous sodium carbonate I mu t e'ltetosn 'zed t tions be,tlvj'e16 i iniiredients being cleaned. This force, the tendency for exist,- yet. the zinc does cimditiom 'and that in not occur until a carbonate. 45.00 High test'calclum 'hypochlorite 5.00 Anhydrous zinc sultate 10.00

Wool. orange 2- -G 25 I mammals has Percent Phosphate monobydrate Wool Qran ge, 2-G ".25

t will be time use the, above formulas that the composition is solid. being a mixture 01 ingredients named. These are to be ounces per Isl- 'sarily a solution of these ingredients unchanged.

there maybe reac- I when water is prese'n'hf thatf'new compounds are formed that even f"PI P1 -s,.may be formed; that thesolution arrivesatsonie equilibrium composition at defconditions-and isvariable with change of use this bath may chance sae d' rabli" is tend to rormand they may iorm in use oithe bath for cleaning.

'Ihe inhibiting action may be due to formatlonforj an:

quen'tl'y in chemical action there is a force tendin8' to produce a; certain result. The action does certain threshold value of the force is attained, yet the mere existence of vital'iactor in a process. Such a conditlonhasbeen observed in studying', the present invention, but there is reason to believe that itfis not the only instance oi such conditions. This observation relates to the presence of zinc in the bath.

There have been observed. certain conditions under which zinc from the solution plates out, electrochemically or galvanically, onto the metal indicates threshold value for a zinc-depositing force has been" exceeded, resulting in the zinc deposition. n the low side of this limiting value for the zinc to plate out must I V not deposit visibly. It may be depositing invislbly at a rate equalto or composition. Precipitatesnot form in making a solution, but may to inhibiting him on the metal, or to thet'endency to form an'f inhibiting film. Fre-' that a certain Example No.2

. Per cent Trisodium phosphate monohydra'te 30. 00 Anhydrous sodium carbonate 39. 75 High test calcium hypochlorite.. 6. 00 Anhydrous zinc su'liate 9. 00 Sodium metasilicate- 15.00 v Wool Or nge 2-G .25

Sample No 3 Percent Trlsodium phosphate monohydrate.. '42. 25 Anhydrous sodium carbonate 42. 50 High test cflollim ynochlorite 5. 00 Anhydrous zinc suliate.. 10. 00 Wool Orange fi-G...-... 25 Example No. .4

Pcrcent .powderedlborax (NGsBsOrJOHzQ) 24. 75

mon alkaline detergents, but it is preferred that i bination consists of mixture in the present invention '-ialls in the inhibiting forms of sodium silicate,

silicate is preferred to the force without a visible result'thereirom, is a less than a rate at which it is dissolved, so that the net result is no deposition.

It is well recognized tendency to plate onto a metal, there is little or no tendency for the metal to be dissolved by the plating solution. From these facts and observations it is believed that the presence of zinc in the solution is an important factor conto the inhibiting action of thecomposition. It is quite likely that the zinc in solutionv acts to alter the potential diiierence' between the bath and the metal to be cleaned, from what the potential would be if the zinc were absent.

, However, the action of the soluble zinc appears to be Joint with other ingredients.

Alkaline detergent part The invention may be practiced with the combe used, in order to protect workers from caustic burns. Mixed alkaline detergents are preferred, and a line mild comtrisodlum phosphate monohydrate, anhydrous sodium carbonate (soda ash) and sodium metaslllcate (NaaSlOa.5HzO). This has the advantage oi protecting iron, zinc, tin and aluminum surfaces. Borax may trisodium phosphate monohydrate for the pro tectlon oithese metals; Whe're sodium metasilicate is omitted from the mixture of alkalis, the composition does not protect aluminum, but it does protect the zinc, iron and tin surfaces. Example No. 3 is an example of a composition which is not eflective .on aluminum under the regular condition oi commercial usage. The alkaline detergent part of the whole composition may vary in a wide manner. In the final line detergent part, but as to aluminum it also part. There are several may vary the eiilciency or limiting proportions for a givenfset of conditions. The sodium metaothers, such as sodium orthosllicate because .in the dry solid composition it creates better stability.

solid mixture. the examples are given in terms In making a bath directly the other salts may be The two ingredients of this part ofthe compositionmay vary in their ratio to each other, and-there will of course be one ratio. which. is more eiiective for a certain alkaline agent or combination of them. This emcient ratio mayalsovary for the conditions of use, and with variations in the ratio between the alkaline part and therei'ore not possible m te efilcient'ratioL" V The commercially preferred ratio and form is l-part of calcium ypocblorite (high test comthat where there is a be substituted for the.

and their specific effects ouncesper gallon. This mercially defined ashaving 70 to 72% available of 1 part of commercial high test" calcium hypochlorite .and Zparts of anhydrous zinc sulphate. Ifthislast ratio is reversed the desired effect is not obtained. The critical limit is not subject to determination unless exact specifications for use are given, and then there must be considered the extent to which the bath is allowed to deteriorate in use, before it is considered non-effective. v

The important ingredient in .the commercial high test calcium hypochlorite is the combination or compound of calcium, oxygen and chlorine. The sodium chloride present in the form described is not any essential part of the invention, but its presence obviously plays a part in determining crictical proportions of the essential ingredients for any set of conditions. There are on the market various forms of high test calcium hypochlorite, and in addition to the form having sodium chloride, there is a form having calcium chloride instead of" sodium chloride.-

used in the composition with appropriateadjustments, but it is not preferred This may be where a solid powder is marketed on account of the hygroscopic nature of calcium chloride.

The examples C. or. higher and at the boiling point forexten sive periods of time longer than commercially used to effect cleaning, such as 8 hours and even to 48 hours. -The eifectivenessof the inhibitor may be appreciated by alkaline agents alone in the same concentration (such as 85% ofthe to 8 ounces per gallon) at 70 0., give corrosive action on both aluminum and tinned ware in a few minutes, and immediately at 100 C.

Formula No. 3 is exceptional in that it will deposit zinc upon tinned were when the concentration is too high, for example over about 5 is striking evidence of v -a function for zinc in the bath, at lower concentrations where it is not deposited. The tendency to deposit is no doubt an important part of the inhibiting forces.

The composition is preferred in a form which may be economically marketed. Hence ingredients are chosen whichmay be mixed to remain stable and non-reactive. The available chlorine from the hypochlorite may be fugitive and its retention is important. 'Absence of'water is desirable to'keep the mass stable. Steel drums are suitable containers for inducing stability in the compositions given. Although there may be water of crystallization in some of the compon'ents (particularly the borax, and the trisodium phosphate monohydrate) it is so closely bound that it is not detrimental to stability.

the fact that any of the- When the composition is dissolved reactions occur which vary with the composition and conditions. The bath may even become milky with some precipitate or insoluble suspension. Transient films may be formed on the. metal to be cleaned, yet the cleaning action without deleterious action on the metal is effected. The baths may be boiled, for example for 8 hours, with little loss of available chlorine. The bath itself is stable at the commercially useful-dilution.

It is to be understood that the bath itself is the functioning composition of the invention,

and that it may be described as the reaction product of the constituents named in the formulas. One could make up the bath directly, and then there is more latitude in choice of ingredients. For example, sodium hypochlorite may be used in place of calcium hypochlorite. The substitution cannot readily be made in the solid powder form because sufliciently strong sodium hypochlorite is not available in solid form. The

calcium form of hypochlorite is merely a means to employ hypochlorite in a .strong solid form which with other ingredients produces a stable composition. The alkali emulsifles or saponifies the grease and fat and readily cleans other dirt or food residues.

The invention has several aspects as set forth herein. The formulas may be changed considerablyfrom the examples given as indicated by the scope of the appended claims.

The present application is specific to our co pending application Serial No. 220,346, filed July 20, 1938, as a continuation in part of this application with claims generic to the matter claimed herein.

We claim:

l. A corrosion-inhibiting alkaline composition for cleaning zinc, iron and tin ware in a solution thereof at from cold to boilingtemperatures consisting essentially of about of water soluble inorganic alkaline detergent, about 5% to 6% of a solid hypochlorite salt of a metal from the group consisting of alkali metals and alkali earth metals, and about 9% to 10% of watersoluble zinc salt.

2. A composition according toclaim 1 in which the zinc salt is zinc sulphate.

3.. A composition according to claim 1 in which the hypochlorite salt is calcium hypochlorite.

4. A composition according to claim 1 in which the alkaline detergent material is a mixture of anhydrous sodium carbonate and trisodium phosphate monohydrate.

5'. A composition according to claim 1 which is useful in addition for aluminum ware in which 'part of the alkaline detergent is a sodium silicate in the amount of about 15% to 20% of the composition. V

6. A corrosion-inhibiting alkaline composition for cleaning zinc, iron, tin and aluminum ware in a solution thereof at from cold to boiling temperatures consisting essentially of from about 65% to 70% of water soluble inorganic alkaline detergent, from about 15% to 20% of sodium silicate, about 5% to 6% of calcium hypochlorite, and about 9%to 10% of zinc sulphate.

7. A corrosion inhibiting mixture for addition to a water soluble inorganic alkaline detergent to render a bath of such material non-corrosive on'zinc, iron and tin ware at from cold to boiling als, and about 2 parts of salt.

8. The method oi. inhibiting the action of aqueous solutions of inorganic alkaline detergents a water-soluble zinc upon zinc, iron and tin ware at temperatures.

prises adding to the detergent solution having v of zinc, iron'a'nd water-soluble zinc salt.

10. A corrosion-inhibiting mixture for addition.

to a water "soluble inorganic alkaline detergent to render abath 'of such material non-corrosive tin ware at from cold to boiling temperatures, which consists of about 1 part of als, and about 2 parts of zinc sulphate. l .CARROLL L. GRIFFITH.

LLOYD A. HALL. 

